Effect of Cuff Pressure Assessment Methods on Postoperative Complications in Breast Surgery

The Effect of Endotracheal Tube Cuff Pressure Assessment Methods on Postoperative Complications in Patients Undergoing Elective Breast Surgery: A Randomized Controlled Trial

Endotracheal intubation is a standard procedure used to secure the airway during general anesthesia. A key component of the breathing tube is the "cuff," a balloon-like device that is inflated to seal the airway and prevent aspiration. However, if the pressure within this cuff is too high, it can restrict blood flow to the tracheal lining, leading to complications such as postoperative sore throat, hoarseness, and difficulty swallowing (dysphagia).

Currently, there are various methods to monitor and adjust this pressure. In many clinical practices, the pressure is adjusted subjectively or checked only once at the beginning of the surgery. These methods may allow pressure to exceed safe limits (typically 20-30 cmH₂O) or fluctuate during the procedure, potentially causing tissue irritation. This randomized controlled trial aims to compare three different methods of assessing and maintaining endotracheal tube cuff pressure to determine which is most effective at reducing postoperative complications. The study focuses on women undergoing elective breast surgery, a group chosen because the surgery typically lasts 1-3 hours and does not involve major changes in head and neck position, allowing for a clear assessment of the cuff pressure methods.

Participants will be randomly assigned to one of three groups:

• Continuous Monitoring Group: Cuff pressure is monitored continuously using a pressure indicator and maintained within the 20-30 cmH₂O range throughout the surgery.
• Manometer Group: Cuff pressure is measured and set to 20-30 cmH₂O using a manual manometer once, immediately after intubation.
• Control Group (Minimal Occlusive Volume): The cuff is inflated with the minimum amount of air required to prevent an air leak, without using a pressure gauge.

Researchers will assess patients for sore throat, cough, hoarseness, and swallowing difficulties at 0, 1, 12, and 24 hours after surgery to identify the safest and most comfortable method for airway management.

This prospective, randomized, parallel-group, single-blind clinical trial investigates the efficacy of different endotracheal tube cuff pressure monitoring techniques in preventing postoperative airway morbidity. The study will be conducted at the İzmir Kâtip Çelebi University Atatürk Training and Research Hospital, Department of Anesthesiology and Reanimation.

The study population consists of female patients aged 18-65 years, classified as ASA I-III, who are scheduled for elective breast surgery under general anesthesia requiring endotracheal intubation. Breast surgery patients were selected as the target population because they represent a homogenous group (typically healthy females), undergo procedures of moderate duration (1-3 hours), and remain in a fixed supine position without significant head-neck manipulation, thereby minimizing confounding variables that could affect cuff pressure.

Study Procedures and Randomization: A total of 90 eligible patients will be enrolled. After providing informed consent, participants will be randomized into three groups with a 1:1:1 allocation ratio. Randomization will be performed using a computer-generated random sequence (via Research Randomizer, randomizer.org) to ensure unbiased assignment. The allocation sequence will be concealed from the investigators until the patient has been successfully intubated.

The three study arms are defined as follows:

• Continuous Pressure Indicator Group: Cuff pressure will be continuously monitored and maintained within the therapeutic range of 20-30 cmH₂O using a continuous pressure indicator device throughout the surgery.
• Manometer Group: Following intubation, the cuff pressure will be measured once using a manual manometer and adjusted to the 20-30 cmH₂O range. No further adjustments will be made unless clinically indicated.
• Control Group (Minimal Occlusive Volume): The cuff will be inflated using the "minimal occlusive volume" technique, wherein the cuff is inflated with the minimum volume of air required to prevent audible air leaks. No objective pressure gauge will be used.

Anesthesia Protocol: All patients will receive a standardized anesthesia protocol. Induction will be achieved with appropriate intravenous agents, and intubation will be performed by the same experienced anesthesiologist to ensure consistency. Anesthesia maintenance will be uniform across all groups. The study excludes patients with a history of difficult intubation, recent respiratory tract infections (within 6 months), preoperative sore throat/hoarseness, or operative times exceeding 3 hours.

Data Collection and Outcomes: The primary outcome is the incidence and severity of postoperative sore throat. Secondary outcomes include hoarseness, cough, dysphagia, laringospasm/bronchospasm, hemorrhage, and recovery times (extubation time, time to spontaneous respiration, and PACU stay duration).

Outcomes will be assessed at four specific time points:

• 0 hours (immediately post-extubation)
• 1 hour (in the Post-Anesthesia Care Unit - PACU)
• 12 hours (on the ward)
• 24 hours (postoperative day 1)

A four-point scale (0-3) will be used to grade symptoms (e.g., 0=None, 1=Mild, 2=Moderate, 3=Severe). To ensure blinding, the postoperative symptom assessment will be performed by a researcher who is unaware of the patient's group assignment.

Statistical Analysis: Sample size calculation indicated that 81 patients are required to detect a significant difference (effect size f=0.41, power=0.90, alpha=0.05), which was increased to 90 to account for a 10% dropout rate. Data will be analyzed using SPSS 26.0. Continuous variables will be analyzed using ANOVA or Kruskal-Wallis tests depending on normality, and categorical variables will be analyzed using Chi-square or Fisher's exact tests. Repeated measures (time-dependent changes) will be analyzed using the Friedman test.

Inclusion Criteria:

• Female patients aged 18 to 65 years.
• Patients classified as American Society of Anesthesiologists (ASA) physical status I, II, or III.
• Patients scheduled for elective breast surgery requiring general anesthesia and endotracheal intubation.
• Patients who provide voluntary written informed consent to participate.

Exclusion Criteria:

• Patients with a history of Chronic Obstructive Pulmonary Disease (COPD) or an asthma attack within the last 6 months.
• Presence of preoperative sore throat, hoarseness, or cough.
• Patients with predicted difficult intubation or those who are difficult to intubate.
• Patients with communication difficulties that prevent accurate assessment of symptoms.
• Patients whose surgery duration exceeds 3 hours.
• Patients older than 65 years.